1. Field of the Invention
The present invention relates to a system for and a method of watching and forecasting long-term weather conditions based on sounds from the earth which are measured by a sensor, and also watching and forecasting changes in natural phenomena and changes in the weather to watch and forecast slope failures including landslides, debris avalanches, snow avalanches, etc.
2. Description of the Related Art
Heretofore, human and property losses resulting from slope failures such as landslides or the like which are abnormal natural phenomena have caused critical damages to regional economies.
If slope failures can be forecast, then it is possible to minimize human and property losses caused thereby, resulting in large economic advantages.
Therefore, there have been steady demands for systems to predict slope failures such as landslides or the like and evacuate local people from the hazardous area quickly.
It is desirable to predict long-term weather changes over more than one month in order to avoid the danger of natural disasters such as slope failures, make agricultural activities efficient, and allow various events to be scheduled easily.
Heretofore, a correlating process, a periodic process, and an analogous process have been employed to predict long-term changes in the weather over more than one month, i.e., long-term changes in atmospheric conditions and various atmospheric phenomena including snow, rain, wind, thunder, etc.
These predicting processes forecast long-term weather changes according to a statistic approach based on empirical rules that are created because physical laws about the weather are not clear enough, unlike short-term weather forecasting processes for predicting weather changes over about one week, which are characterized by the use of highly sophisticated meteorological observation devices, a large number of meteorological observation sites, and a large number of meteorological observation cycles. The long-term weather forecasting processes predict long-term weather changes based on an average of predicted data over a plurality of years in the past, e.g., over several decades. The prediction data produced by these long-term weather forecasting processes are not necessarily highly accurate, although these processes are capable of roughly predicting long-term weather changes. It is almost impossible for the long-term weather forecasting processes to predict accurately whether it will be hot or cold on a particular day in the future, e.g., after 3 months or 6 months from now.
There are two known techniques to watch a landslide. According to the first technique, an Invar wire is extended under tension between two points, and the distance between the points is measured from an elongation of the Invar wire. According to the second technique, a water pressure meter is placed in a hole formed in the ground by boring, and a pressure transmitted by a fluid present in a pore in the soil or rock, i.e., a so-called pore water pressure is measured.
The first technique which employs an Invar wire suffers a fatal defect in that it is unable to detect a slope failure which occurs in a position away from the two points. One solution is to use a number of Invar wires installed in different positions. However, land areas which are used for agricultural activities limit the number of locations available for installing Invar wires because Invar wires would lower the efficiency of agricultural activities. The cost of a system for measuring changes in the distances between points where many Invar wires are installed is considerably large.
The second technique which employs a water pressure meter placed in a hole formed in the ground is disadvantageous in that it is highly expensive and it is impossible to perform boring on all dangerous land regions. Another problem of the second technique is that available experimental data are definitely not enough for identifying a direct causal relation between a change in the pore water pressure and a slope failure. In addition, the second technique cannot meet a quick need for landslide monitoring because it usually takes several days to form a hole in the ground by boring.
Consequently, there is not any satisfactory process for locally and accurately predicting a slope failure.